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For the most part, vitamins are obtained from the diet, but some are acquired by other means: for example, microorganisms in the gut flora produce vitamin K and biotin; and one form of vitamin D is synthesized in skin cells when they are exposed to a certain wavelength of ultraviolet light present in sunlight.
Calcifediol is further hydroxylated by the kidneys and certain immune cells to form calcitriol (1,25-dihydroxycholecalciferol; 1,25(OH) 2 D), the biologically active form of vitamin D. [3] Calcitriol attaches to vitamin D receptors, which are nuclear receptors found in various tissues throughout the body. The discovery of the vitamin in 1922 ...
Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium ...
Biotin (also known as vitamin B 7 or vitamin H) is one of the B vitamins. [ 1 ] [ 2 ] [ 3 ] It is involved in a wide range of metabolic processes, both in humans and in other organisms, primarily related to the utilization of fats, carbohydrates, and amino acids. [ 4 ]
Vitamin B 12 is produced in nature by certain bacteria, and archaea. [71] [72] [73] It is synthesized by some bacteria in the gut microbiota in humans and other animals, but it has long been thought that humans cannot absorb this as it is made in the colon, downstream from the small intestine, where the absorption of most nutrients occurs. [74]
The three vitamin precursors used in these salvage metabolic pathways are nicotinic acid (NA), nicotinamide (Nam) and nicotinamide riboside (NR). [6] These compounds can be taken up from the diet and are termed vitamin B 3 or niacin. However, these compounds are also produced within cells and by digestion of cellular NAD +.
Vitamin B 10: para-aminobenzoic acid (pABA or PABA), a chemical component of the folate molecule produced by plants and bacteria, and found in many foods. [ 40 ] [ 41 ] It is best known as a UV -blocking sunscreen applied to the skin, and is sometimes taken orally for certain medical conditions.
A biomolecule or biological molecule is loosely defined as a molecule produced by a living organism and essential to one or more typically biological processes. [1] Biomolecules include large macromolecules such as proteins , carbohydrates , lipids , and nucleic acids , as well as small molecules such as vitamins and hormones.